1. Field Of The Invention
This invention generally concerns tumbling media for use in tumbling non-magnetic parts, and more particularly relates to adapting a non-magnetic tumbling element with a ferro-magnetic insert to facilitate the separation and removal of the media from the work via magnetic separation.
2. Description Of Prior Developments
Tumbling media has long been used to clean, polish, debur or abrade various workpieces following such work forming operations as casting, molding, stamping, machining, etc. The media is typically loaded into a rotary drum or tumbler barrel such as described in U.S. Pat. No. 3,623,706 along with the workpieces whereby rotation of the drum causes the media to mix with and impact the workpieces. This mixing and tumbling action effects a gradual cleaning or abrading action over the surfaces of the workpieces.
After the workpieces have been adequately processed in the tumbler, they must then be separated from the tumbling media. Conventional sorting techniques including mechanical sifting and magnetic sorting have been used with generally adequate results in those instances when such methods may be efficiently employed. However, mechanical sifting with the aid of a sieve or screen is usually limited to those cases where there is a significant difference between the size of the workpiece and the size of tumbling media elements. Moreover, magnetic sorting is generally limited to those cases where either the workpiece or the media is magnetic so that magnetic attraction of either the workpiece or the media will effect separation and sorting.
A separation problem arises where the tumbling media and the workpieces are both non-magnetic and poorly suited to mechanical separation techniques such as sifting. For example, plastic, ceramic or rock-like tumbling media are frequently used to polish various non-magnetic metallic parts formed from materials such as brass and aluminum. In this case, sorting by hand has been required.
Hand sorting the media from the workpieces is a labor intensive process and brings with it most drawbacks associated with manual operations including increased cost and reduced output. Hand sorting is further complicated when the workpieces are of an awkward shape and requiring significant manipulation.
Another problem arises when a lightweight tumbling media such as a plastic media is used to polish a workpiece. Because of its relatively small mass, lightweight tumbling media does not develop adequate kinetic energy during tumbling to impact the workpieces with sufficient impulse to rapidly abrade or polish the workpiece surfaces. This usually requires a protracted tumbling operation to allow sufficient time for the media to slowly complete the tumbling process.
Accordingly, a need exists for a tumbling media which may be quickly and easily separated from a batch of non-magnetic workpieces by a magnetic separation process. A need also exists for a tumbling media having a non-magnetic impact surface for use in tumbling non-magnetic parts and which is adapted for magnetic separation techniques. Finally, a need exists for increasing the kinetic energy of lightweight tumbling media i.e. non-magnetic tumbling media in order to achieve a more rapid tumbling process.